DESCRIPTION OF PLATES 
Pi/ATJS XXIII. Parts of sweet-potato plants, showing the presence of pycnidia: A, On 
the stem just above the ground; B, on the root. 
XXIV. Portion of sweet-potato vines several feet from the hill, showing the 
results of a natural infection of the foot-rot fungus. The organism 
was recovered from these vines before being photographed. 
XXV. Microscopic characters of the foot-rot fungus: A. Section through 
a pycnidium on the root; B, section through a pycnidium on the 
stem; C, hyphae, from artificial culture; D and F, chlamydospore- 
like bodies found on the host and in some culture media; F, 
pycnospores; G, club-shaped bodies often found in pycnidia; II, 
germinating pycnospores. 
XXVI. Two sweet-potato plants in pots, demonstrating the parasitism of the 
foot-rot fungus: A, Inoculated; B, not inoculated. 
XXVII. Nine-day-old cultures on synthetic agar: A, The conidial stage of 
Diaporthe batatatis; B, Plenodomus destruens. 
XXVIII. Sweet potatoes inoculated with Plenodomus destruens: A, Inoculated 
at the end; B, a section of A showing extent of rot; C, inoculated 
at the side; D, section of C showing the extent of rot. 
(274) 
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